1. Field of the Invention
This invention relates in general to method and apparatus for an optical four-gate coupler which includes an incoming and out-going fiber optical waveguide of a first relatively large diameter and at least one additional large fiber and one smaller optical fiber are coupled together such that the fibers can be cut at the coupling point transverse to the axis of the fibers after which the ends are coupled together in an offset fashion so as to provide a four-gate optical coupler.
2. Description of the Prior Art
The publication entitled "Planar Input-Output Couplers In Thick-Film Technology for Multimode Optical Fibers" by H. H. Witte and V. Kulich, Siemens Forsch.-u-Entwickl.-Ber. Volume 8, No. 3, 1979, Pages 141-143 discloses optical four-gate couplers which have a pair of input multimode optical fibers connected to a pair of output fibers and in which the diameter of all the optical fibers are of equal size such that the degree of input coupling is equal to the degree of output coupling. If such couplers are employed in optical data buses with T network structures, this results in an output coupling loss which increases linearly with the number of subscribers.